Variable output refrigeration



May 4; 1954 W. E. DAVIS VARIABLE OUTPUT REFRIGERATION SYSTEM Original Filed Nov. 15, 1950 William E. Davis INVENTOR.

BY m 6 EM ATTORNEY Reiwled r 1954 Re. 23,821

UNITED STATES PATENT OFFICE VARIABLE OUTPUT REFRIGERATION SYSTEM William E. Davis, Houston, Text.

Original No. 2,603,954, dated July 22, 1952, Serial I No. 195,885, November 15, 1950. Application for reissue January 12, 1953, Serial No. 330,933

3 Claims. (01. 62117.1) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

1 This invention relates to control apparatus for compressors of the gaseous fluid type and more particularly to control apparatus for air conditioning and refrigerating systems of the com- It is another object of this invention to proof a compressor without causing excessive changes in pressure in the low side of the system as pression type in which the system, including the 5 when the gas is by-passed from the high side compressor, uses a condensable gas which is kept to the low side. confined in the system. It is also an object of this invention to provide The general object of this invention is to proan improved system for completely shutting off vide a simple and improved apparatus wherein the refrigerating system where it is impractical the input of mechanical energy to the compressor to stop the compressor driving motor such as and the transfer of thermal energy of the system when large motors are used or when the motor can be controlled without stopping the compressor is also used for other purposes. or without varying the speed of the compressor. Other and further objects are apparent when It is anobject of this invention to provide a the specification is considered in connection with system of controlling and limiting the amount of the drawings in which: mechanical energy used to drive the compressor Figure 1, the single figure, partially in section, and'the amount of thermal energy transferred by and partially diagrammatic, represents a typical the system, even though the compressor may be compressor type refrigerating system employed in driven by a source which necessitates its operaconnection with this invention. tion over a range of speeds such as when used The refrigerating system I includes therewith a in connection with air conditioning or refrigeratcompressor 2 having an oil sump 3 to be hereining apparatus in automobiles, trucks, railway after described in connection with specific feacoaches, and the like, where the compressor is tures of this invention, a shaft 4 journalled in driven from the motor or the wheels of the vehicle. the compressor body, a. crank arm 5 rigidly con- It is another object of this invention to control nected to the shaft 4, a piston rod '6 pivotally input of mechanical energy and the transfer of connected to the crank 5 at I and to the piston I thermal energy so that it will approach the reat 8. The rotation of the shaft 4 causes the piston quired load conditions without stopping or varyto reciprocate in the cylinder II]. On the downing the speed of the compressor. stroke of the piston the inlet valve H is opened Another object of this invention is to stop or so the fluid may enter the cylinder, and on the limit the flow of gas through the valves of the up-stroke of the piston 9 fluid is discharged upcompressor, without varying the speeds of the wardly through the outlet valve I! to pass out compressor, so that the amount of gas flowing into the discharge line I3. through them will be reduced whenthe amount The refrigerating system herein described operof refrigeration required is reduced, rather than ates conventionally by delivering the fluid in the increasing the amount of gaspassiilgthrough the form of a hot high pressure gas into the concompressor as is done by the byr-pass' systems denser coils [4 where the heat is removed therewhere the outlet of the compressoris led back from with the result that the gas liquefies and into the inlet of the compressorraising -the back. :is; delivered, preferably by gravity, itno the repressure and increasing the total lamount of gas ceiver i5. From the receiver l5 the liquid refrigpassing through the compressor.

erant flows outwardly into the connecting line. 16 Another object of this invention; limit the to the expansion valve I]. This valve i'l jis of Power p t and p t 01' thQcOmDl S-SM S01 theconventional type designed to receive a fluid that it will not be loaded beyond its rated capacat a higher pressure and to deliver the fluid thereity even though it should be run ataspeed which from at a lower pressure. 4 would normally cause it to overload and break From the expansion valve I! the refrigerant down. passes into the evaporator means, shown herein Another object of this invention is to keep the as a series of coils I8. These coils pass through refrigeration system itself from becoming overa'space is from which it is desired to remove a loaded or freezing up even though the speed of quantity of heat. the compressor should exceed its normal speed. The lowering of the refrigerant pressure result- Another object of this invention is to provide ing from its passage through the valve l1 causes a method of reducing the starting load on the it to evaportae and to absorb heat from the space compressor used in a refrigeration system of the IS in which the evaporator I8 is located. It then do p s ion typepasses into the return line 20.

The return line connects at 23 into a valve means 24 and the outlet side of the valve means 24 is connected at 25 into the inlet chamber 21 of the compressor. The path of refrigerant then leads through the valve ll into the cylinder Ill and thence through the valve l2 into the outlet chamber 28 which communicates with the high pressure, or discharge line l3, as has been hereinabove described.

The connection 2| is shown inserted in the return line 20, outwardly of, or more properly on the inlet side of the valve means 24. A line 22 from this connection 2| leads to the sump 3.

The compressor 2 should be a type which has no direct or internal connection from the inlet port 25 or inlet chamber 21 or inlet valve II to the enclosed oil sump 3. This compressor 2 is shown as a conventional, single cylinder piston type with valves II and I2 located in the head plate 26. A multiple cylinder compressor may also be used or any other type of compressor which has a closed oil sump and has no connection between the oil sump and the inlet of the compressor. However, a conventional piston type of compressor with inlet valve located on, or in may be closed or partially closed by any of the variable conditions available for controlling the valve means. These variables may be the tem- 4 in which a liquid refrigerant is evaporated to absorb the heat of vaporization of the refrigerant, the total amount of refrigeration produced is directly proportional to the total mass or weight of the liquid evaporated, such weight being equal to the weight or mass of the vaporized gas produced. As this gas must be re-condensed by the compressor, the total amount of refri eration produced in the closed system will also be directly proportional to the weight or mass of the gas passing through the compressor. The mass of gas passing through the compressor will be determined by the mass of gas forced into each cylinder or compression chamber at the time of .maximum displacement, such maximum disrelatively small at this point) varies directly as the discharge pressure, the speed of the compressor, [the suction pressure] the flow of gas 1 through the suction or discharge line, or any other variables which need be limited or controlled. An automatic mechanical valve may be employed which is controlled by any of the available variables, or also a combination of one or more of the above mentioned types of valves may be used, either singularly or in multiples.

Line 22 is connected to line 20 preferably at 23 near the inlet to valve means 24 so that it will provide a gas pressure in the oil sump 3 which will not change rapidly when valve means 24 is operated. This line 22 is arranged so that any oil which may leak into the system will be returned, preferably by gravity, to the oil sump 3.

For convenience pressure in that portion of the system between the downstream side of the control valve 24 and the inlet valve l l is referred to as control pressure.

When valve means 24 is shut off no gas will pass through the compressor so there will be no refrigerant circulating through the system which will cause it to become inoperative until it is desired to start the process again, at which time valve means 24 is opened and the gas is again allowed to flow. The oil then will be returned through line 22 (or 22'). The energy consumed by the compressor when the valve is closed will be only that required to overcome the losses of friction and the losses introduced by the leakage of the valves and pistons. If the valve means 24 is partially closed, the amount of energy consumed by the compressor and the amount of heat transferred by the system will be proportional to the amount the valve is opened.

In any refrigeration or air conditioning system the absolute pressure (Boyle's law). As the volume of gas in the cylinder or chamber, at each time of maximum displacement, is constant, then the density of the gas will be directly proportional to the mass. From this it follows that the mass or weight of gas flowing through the compressor is directly proportional to the absolute pressure of the gas at the input. Thus in a refrigeration system of this type, using a given compressor and refrigerant, the amount of refrigeration produced per stroke or revolution of been developed wherein the inlet pressure to the I compressor may be varied without causing these variations in pressure to be transferred directly to other parts of the system [the oil sump] where [the lowering of the] abrupt pressure changes may cause [such] difficulties. [as foaming of the oil, leakage of air into the system, and inoperation of the oil pump, if used] Broadly, therefore, this invention considers varying the amount of heat transferred in a refrigeration system and the input of mechanical energy thereunto by controlling the pressure on the inlet of the compressor, without [lowering the crankcase or evaporator pressure] causing abrupt pressure changes in other parts of the system.

What is claimed is:

[1. A closed refrigeration system including a compressor having an inlet, a discharge line, and a sump for compressor oil, a refrigerant to be supplied to the compressor through the inlet as a low pressure gas, compressed therein, and expelled through the discharge line as a high pressure gas, a condenser connected to the discharge line, means connected to the condenser providing a. restricted passage to receive refrigerant from the condenser and to discharge it at a lowered pressure, an evaporator connected to the outlet from said passage to receive the refrigerant therefrom and permit it to evaporate and absorb heat from the space around the evaporator, a return line from the evaporator to the compressor inlet, a control valve means interposed in said return line, to provide a control pressure between said control valve and the compressor inlet isolated pneumatically and hydrostatically from the sump so that the control pressure is not communicated directly to the sump, and means providing a passage from the sump to a gas filled portion of the system downstream from aaeai said restricted passage and upstream from the control valve, whereby a pressure other than the control pressure is exerted on the sump and any oil which may leak into the system will be restored to the sump] [2. A closed refrigeration system including a compressor having an inlet, a discharge line, and a sump for compressor oil, a refrigerant to be supplied to the compressor through the inlet as a low pressure gas, compressed therein, and ex,- pelled through the discharge line as a high pressure gas, a condenser connected to the discharge line, means connected to the condenser providing its inlet connected to said compressor discharge, means connected to the outlet of said condenser providing a restricted passage from the conto limit the mass of gas flowing to said compresa restricted passage to receive the refrigerant from the condenser and to discharge it at a lowered pressure, an evaporator connected to the outlet from said passage to receive the refrigerant therefrom and permit it to evaporate and absorb heat from the space around the evaporator, a return line from the evaporator to the comcontrol valve whereby a pressure other than the control pressure is exerted on the sump and any oil which may leak into the system will be restored to the sump.]

[3. In a'refrigeration system wherein apparatus is provided including a piston-type compressor with one end of a piston therein in communication with a gas-tight crankcase for the compressor which is adapted to contain a lubricating oil and wherein the opposite end of said piston is in communication with suction and discharge conduits controlled by conventional compressor suction and discharge valves, respectively, and wherein said suction and discharge conduits are respectively connected to evaporating and condensing means of a closed refrigerating system, the improvement which comprises in combination therewith of a flow control means in said suction conduit and a conduit between said crankcase and the suction conduit upstream of said control means] [4. The apparatus of claim 3 wherein the point at which said last mentioned conduit connects to said suction conduit is at a vertical level above its inlet to said crankcase whereby a lubrlcant in a refrigerant passing through said compressor can flow to said crankcase] [5. A compressor system which comprises, in combination, a piston-type compressor having one end of a piston therein in communication with suction and discharge conduits controlled by conventional compressor suction and discharge valves, respectively, and having a sump in communication with the other end of said piston and adapted to contain a lubricating oil, a

flow control means in said suction conduit and a conduit between said sump and said suction conduit upstream of said flow control means] 6. A refrigeration system comprising in combination with a prime mover having duties requiring speeds of operation independent of the sor and means providing a passage from the oil retaining space to a portion of the system downstream from said restricted passage and upstream from the control valve means, whereby maximum mass of refrigerant intake to said compressor may be controlled independently of its speed without rapid variation in the pressure in saidoil retaining space.

['Z. A refrigeration system comprising in combination with a prime mover having required speeds of operation independent of the amount of refrigeration required, a compressor connected to said prime mover to be driven thereby at speeds dependent on the speed of said prime mover and having an inlet, a discharge, and an; oil retaining space, a condenser having its inlet connected to the discharge from said compressor, means connected to the outlet of said condenser providing a restricted passage from the condenser, and an evaporator connectedto the outlet from said passage, a return line from the said oil retaining space being in communication with a gas iilledportion of the system downstream from the compressor discharge and upstream from the control valve whereby a pressure other than the control pressure is exerted on the oil retaining space and any oil which may leak into the system will be restored to the oil retaining space] i [8. Refrigeration apparatus adapted for use in a vehicle comprising a compressor having a driving connection adapted to be connected to a part on said vehicle which moves with respect to the remainder o1 the vehicle as the vehicle travels from place to place, whereby said compressor will be driven at speeds depending upon the speed of movement of said part of the vehicle to which it is connected, said compressor having also an inlet, a compression space, an outlet, and an oil retaining space, a control valve connected to the inlet for controlling the intake to said compressor, and connections to the entrance of said valve and from the outlet of said compressor, said connections, valve, compression space, inlet and outlet, providing a refrigerant passage, said oil retaining space being isolated from that portion of the refrigerant passage between said control valve and said compressor outlet and being in communication with said refrigerant passage beyond the limits of that portion of the refrigerant passage downstream from said control valve and upstream from said compressor outlet] [9. A compressor system which comprises in combination, a compressor having an inlet, a compression space, an outlet, and an oil retaining space, a control valve connected to the inlet for controlling the intake to said compressor, connections to the inlet of said valve and from the outlet from said compressor, said connections, valve, compressor space, and inlet and outlet providing a refrigerant passage, said 011 retaining space being isolated from that portion of the refrigerant passage between said control valve and said compressor outlet and said all retaining space being in communication with said refrigerant passage beyond the limits of that portion or the refrigerant passage downstream from said control valve and upstream from said compressor outlet] 10. A refrigeration system comprising in combination with a prime mover having required speeds of operation independent of the amount of refrigeration required, a compressor connected to said prime mover to be driven thereby at speeds dependent on the speed of said prime mover and having an inlet, a discharge, and an oil retaining space, a condenser having its inlet connected to the discharge from said compressor, means connected to the outlet of said condenser providing a restricted passage from the condenser, and an evaporator connected to the outlet from said passage, a return line from the evaporator to the compressor inlet,-a control valve means interposed in said return line to provide a control pressure space between said control valve means and the compressor inlet isolated pneumatically and hydrostatically from the oil retaining space so that the control pressure is not communicated directly to the oil retaining space, said oil retaining space being in communication with a gas filled portion of the system downstream from the compressor discharge and upstream from the control valve means whereby a pressure other than the 3 control valve means including means for controlling and limiting the mass of gas passing through said control valve means independently of the evaporator pressure.

11. A refrigeration compressor system which comprises, in combination, a compressor having an inlet, a compression space, an outlet, and an oil retaining space, an electrically actuated shutofl and metering valve settable to a desired predetermined maximum opening connected to the inlet for controlling the intake to said compressor, connections to the inlet of said valve and from the outlet from said compressor, said connections, valve, compression space, and inlet and outlet providing a refrigerant passage, said oil retaining space being isolated from that portion of the refrigerant passage between said valve and said compression space outlet, and said oil retaining space being in communication with said refrigerant passage beyond the limits of that portion of the refrigerant passage downstream from said valve and upstream from said compression space outlet, whereby the control pressure between the valve and the intake to said compressor may be regulated to any value desired.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS Number Name Date 1,247,209 Bertsch Nov. 20, 1917 1,436,815 Marshall Nov. 28, 1922 1,698,941 Davenport Jan. 15, 1929 1,768,602 Hull July 1, 1930 2,032,230 Small et a1. "Feb. 25, 1936 2,061,599 Smith Nov. 24, 1936 2,301,656 Hirche Nov. 10, 1942 2,418,853 Shoemaker Apr. 15, 1947 

